JP2001224883A - Thread cutter of sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut threads appropriately and to extend the life of a heater by controlling the rise of temperature of the heater not to exceed an appropriate temperature for thread cutting. SOLUTION: The thread cutter comprises a power feeding means 17 for sending electricity to a heater 5 to feed electric power when threads are cut, a time keeping means 20 for keeping the time from the current thread cutting to the start of power feeding to the heater 5 by the power feeding means 17 for the next thread cutting, and a control means 10 for controlling the quantity of the electric power fed to the heater 5 by the power feeding means 17 for the next thread cutting based on the time kept by the time keeping means 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device for a sewing machine that cuts a sewing thread by energizing a heating element, and more particularly, to a thread trimming apparatus for a sewing machine with improved control of energization of a heating element.

[0002]

2. Description of the Related Art Conventionally, a sewing machine, especially an industrial sewing machine, is provided with a thread trimming device for automatically cutting a sewing thread in order to improve sewing efficiency. A certain upper thread and a lower thread can be cut at the same time.

[0003] As such a thread cutting device, for example,
It is known that a moving knife and a fixed knife are provided on the back surface of the needle plate, and the sewing thread is cut by the moving knife, and the sewing thread is cut between the moving knife and the fixed knife to cut the sewing thread.

However, in such a yarn cutting device, for example, when cutting a twisted yarn composed of a plurality of single yarns, each single yarn is separated from the cut portion, and the appearance of the cut portion of the yarn becomes poor. There was such a problem.
In addition, there is also a problem that cutting a thread coated with a special coating slows down a scalpel and causes poor thread cutting.

In order to solve such a problem, a thread cutting device has been proposed in which a heating element which is heated by energization is brought into contact with a sewing thread to melt and cut the sewing thread by heat.

FIGS. 5 to 7 show an example of such a thread trimming device for a sewing machine. As shown in FIG.
The thread cutting device 2 of the sewing machine 1 is provided with a heating element 5 which is disposed near the needle hole 4 on the back surface of the needle plate 3 and generates heat by energization, and a sewing thread 6 (FIG. 6) to be cut off by the heat of the heating element 5. There is a capturing member 7 that captures and urges the heating element 5 to come into contact therewith. Then, at the end of sewing of the work to be sewn by the sewing machine 1, the catching member 7 is rotated by a driving means (not shown) such as a thread cutting solenoid, so that the state shown in FIG.
7, the upper thread 6a and the lower thread 6b, which are the sewing threads 6 to be cut off, are captured by the capturing member 7 and brought into contact with the heating element 5, and the heat of the heating element 5 causes the upper thread 6a and the lower thread 6b. Are melted at the same time.

Further, in such a thread trimming device 2, in order to prevent the sewing thread 6 from being in contact with the heating element 5 and cutting the sewing thread 6 being sewn during the time other than during thread trimming, the heating element 5
Heat is generated only at the time of thread cutting, and the heat generation of the heating element 5 is terminated before the heat of the heating element 5 is transmitted to the surrounding members other than the heating element 5. Control means 10 for controlling the energization so as to flow is used.
That is, as shown in FIG. 8, the control means 10 includes a CPU 12 and a memory 13 connected to a control panel 11.
By controlling the operation of a switch section 16 formed by a relay or the like by a CPU board 15 on which a control circuit 14 and the like are mounted, a predetermined voltage is set by a heater transformer 19 connected to a power supply 17,
Is formed so as to control the energization of the current supplied to the power supply.

[0008]

[Table 1]

More specifically, as shown in Table 1, the control panel 11 can select six heating levels, and the selected heating level is input to the CPU 12. This CPU
Reference numeral 12 outputs a heating command to the switch unit 16 for a normal heating time set by the selected heating level. Then, the switch section 16 controls the output of the heater transformer 19 supplied from the power supply 17, heats the heating element 5 for a predetermined time, and melts the sewing thread in accordance with the thread cutting operation of the sewing machine 1. .

[0010]

When the above-described thread trimming device 2 is mounted on an electronic cycle sewing machine, the electronic cycle sewing machine is characterized in that a sewing pattern can be easily changed. In the cycle sewing machine, thread trimming is performed at a certain free timing. The interval between the two thread trimmings may be 1 second or less.

If the two times of thread trimming are performed at short intervals, the heating element 5 once heated is not completely cooled, and the heating element 5 is energized next time while maintaining a certain temperature. Will be As a result, the maximum temperature of the heating element 5 by the energization after the current becomes higher than the maximum temperature of the heating element 5 by the energization before.

FIG. 9 is a graph showing the temperature change of the heating element 5 when the above-described short-time interval thread cutting is continued.
On the other hand, if the current is repeatedly supplied for a short time, the temperature will rise by about 130 ° C. from the maximum temperature at the time of the first current supply.

This means that the heating element 5 is heated to an unnecessarily high temperature, which not only adversely affects the thread cutting performance of the heating element 5 but also causes the heating element 5 to be heated.
Was to shorten the lifespan.

The present invention overcomes the above-mentioned problems of the prior art, and makes it possible to perform good thread cutting by raising the heating element only to a good temperature for thread cutting. It is an object of the present invention to provide a thread trimming device for a sewing machine that can extend the life of a sewing machine.

[0015]

According to a first aspect of the present invention, there is provided a thread trimming device for a sewing machine, comprising: a power supply means for supplying power by supplying power to a heating element during thread trimming; Time measuring means for measuring the time from when the previous thread trimming is performed to when power is supplied to the heating element by the power supply means during the next thread trimming, and the next thread trimming is performed based on the time measured by the time measuring means. And control means for sometimes controlling the amount of power supplied to the heating element by the power supply means. By adopting such a configuration, the amount of power supplied to the heating element by the power supply means at the time of the next thread trimming is controlled by the time from the previous thread trimming to the next thread trimming measured by the timing means. Since the control is performed by the means, it is possible to increase the maximum temperature of the heating element by energization only to a temperature at which good thread cutting can be performed.

According to a second aspect of the present invention, the thread trimming device for a sewing machine is characterized in that the control means is configured to determine whether or not the current supplied to the heating element is to be supplied based on the time measured by the time measuring means. By controlling at least one of the duty cycle and the supply voltage, the amount of power supplied to the heating element by the current supply means at the time of thread trimming is controlled. And by adopting such a configuration, the current conduction time, the duty cycle of the current conduction time,
The amount of electric power supplied to the heating element can be stably controlled by a suitable element of the different elements called the energizing voltage.

A third feature of the present invention is that the control means corrects the amount of electric power supplied to the heating element to a predetermined reference amount based on the time measured by the time measuring means. It is in. By adopting such a configuration, the power amount corrected to a value smaller than the reference amount, for example, is supplied to the heating element during a short energization interval in which the maximum temperature of the heating element tends to rise, and the maximum The temperature can be controlled more stably.

A feature of the thread trimming device of the present invention according to claim 4 is that reference amount setting means for setting a predetermined reference amount by operation is provided. By adopting such a configuration, a predetermined reference amount can be easily set.

According to a fifth aspect of the present invention, in the thread trimming device for a sewing machine according to the present invention, the control means supplies a predetermined amount of power to the heating element by the power supply means at the time of the first thread trimming after turning on the power to the sewing machine. If the time measured by the timekeeping means exceeds the predetermined time in the next and subsequent thread trimming,
The point is that control is performed such that the amount of power supplied to the heating element is the predetermined amount of power. By adopting such a configuration, control of the amount of power supplied to the heating element can be simplified.

[0020]

FIG. 1 is a block diagram showing an embodiment of a thread cutting device for a sewing machine according to the present invention.
Reference numeral 0 denotes a switch section 1 formed by a relay or the like by a CPU board 15 mounted with a CPU 12, a memory 13, a control circuit 14 and the like connected to a control panel 11 capable of selecting six heating levels.
By controlling the operation of 6, the heater transformer 19 connected to the power supply 17, which is a power supply unit, sets the voltage to a predetermined voltage and then controls the current supply to the heating element 5. . The control panel 11 constitutes a reference amount setting means for setting a heating level, which is a predetermined reference amount, by operation.

In the present embodiment, in particular, the time from when the previous thread trimming is performed to when the power is supplied to the heating element 5 by the power supply means during the next thread trimming is stored in the CPU board 15. A thread trimming interval detection timer 20 is provided as time measuring means for measuring the time.

On the other hand, a heating time control table 13A is stored in the memory 13 in advance. Table 2 shows a specific example of the heating time control table 13A. In Table 2, out of the six heating levels that can be selected, only three heating levels 1, 3, and 5 are described for convenience, and descriptions of the other heating levels 2, 4, and 6 are omitted.

[0023]

[Table 2]

According to Table 2, the reference time for energizing the heating element 5 is 230 ms at the heating level 1, 250 ms at the heating level 3, and 270 at the heating level 5.
However, the shorter the thread cutting interval, the more the heat energy during the previous energization is left in the heating element. Therefore, the shorter the thread cutting interval, the shorter the actual energizing time to the heating element 5. There is a need. Therefore, the energization time for energizing the heating element 5 is set by multiplying the above-described reference time by a smaller coefficient as the thread cutting interval becomes shorter.

That is, this coefficient is 1 if the thread cutting interval is 8 seconds or more, 0.98 if the thread cutting interval is 7 seconds or more and less than 8 seconds,
0.96 for 6 seconds or more and less than 7 seconds 0.93 for 5 seconds or more and less than 6 seconds 0.8 for 4 seconds or more and less than 5 seconds
9, 0.83 for 3 seconds or more and less than 4 seconds, 0.78 for 2 seconds or more and less than 3 seconds, 0.0 for 1 second or more and less than 2 seconds.
7, if it is less than 1 second, it is set to 0.6.

As a result, the energization time is set shorter at the same heating level as the thread cutting interval is shorter. As an example, regarding the energizing time at the heating level 1, 230 ms if the thread cutting interval is 8 seconds or more, 225 ms if 7 seconds or more and less than 8 seconds, 221 ms if 6 seconds or more and less than 7 seconds, and 5 seconds or more 6 214m if less than seconds
s: 205 ms for 4 seconds to less than 5 seconds, 3 seconds to 4
193 ms for less than 2 seconds, 179 ms for 2 seconds or more and less than 3 seconds, 161 ms for 1 second or more and less than 2 seconds
If it is less than seconds, it will be 138 ms.

FIG. 3 is a graph showing the correlation between the clocking time corresponding to the thread trimming interval and the power-on time corresponding to the power-on time in the present embodiment. Although not exactly strictly proportional, the clocking time is long. This shows that the energization time is prolonged if it becomes possible.

In the first thread trimming, the heating time in Table 1 described above, that is, the heating time when the thread trimming interval in Table 2 is 8 seconds or more.

Further, the mechanical configuration of the thread trimming device of the sewing machine according to the present embodiment is the same as that shown in FIGS.

Next, the operation of the embodiment of the present invention having the above-described configuration will be described.

FIG. 2 is a flowchart showing the operation of the present embodiment. To start sewing by the sewing machine, the power is turned on as shown in step ST1. And FIG.
By operating the control panel 11 of FIG. 1 and selecting and setting a heating level suitable for the material and thickness of the yarn from the six heating levels, the set heating level is determined as shown in FIG.
The CPU 12 of FIG. 1 reads this heating level (step ST2). The heating level read from the memory 13 by the CPU 12 is as follows.
It may be performed only once at the start of driving of the sewing machine, or may be performed for each thread cut.

When the CPU 12 reads the heating level, the CPU 12 sets the current supply time of the current supplied to the heating element to a reference time corresponding to the heating level. Is determined.

Thereafter, a predetermined sewing pattern is sewn, and when a thread trimming command included in the predetermined sewing pattern is read, a selection of whether or not a thread trimming command has been issued in step ST4 is made Y (yes). A heating command is issued from the CPU 12 at a predetermined timing determined based on a needle position signal output from a needle position detecting means (not shown), the switch unit 16 is energized, and the heating element 5 is supplied with a predetermined power amount P. Is started and thread trimming is performed (step S
T5). Note that the timing of the thread trimming command and the timing of energizing the heating element 5 do not always match. Then, step ST6
It is determined whether the supply of the predetermined amount of power P to the heating element 5 has been completed. In this embodiment, this determination is made by determining whether or not the energization time from the start of energization in step ST5 has reached the reference time corresponding to the heating level read in step ST2. . Then, in step ST6, when it is determined that the supply of the predetermined power amount P is completed, the process proceeds to step ST7, in which the energization is stopped, and further proceeds to step ST8, in which time counting by the thread trimming interval detection timer 20 starts. Is done.

When the above-mentioned timing is started, step S
It is determined whether or not the time measured corresponding to the thread trimming interval of T9 has exceeded a predetermined time. In the present embodiment, the predetermined time is a reference time corresponding to the case where the above-mentioned coefficient is 1 or more than 8 seconds. If the predetermined time is exceeded, the process proceeds to step ST10, time measurement ends, and the process proceeds to step ST3. Returning, the amount of power to be applied to the heating element 5 is again determined to be the predetermined amount of power P determined at the time of the first thread trimming after the power is turned on.

On the other hand, if the measured time does not exceed the predetermined time in step ST9, the process proceeds to step ST11, and the next thread trimming command is issued. Then, the process proceeds to step ST12, and the time measurement is completed. , Table 2
The energization time in the next thread trimming is determined as the corrected power amount Pn by the heating time control table 13A shown in a specific example (step ST13). Then, the process proceeds to step ST14, in which the energization with the correction power amount Pn is started, the heating element 5 is heated, and the next thread trimming is performed. Then, the process proceeds to step ST6, in which the correction power amount P for the heating element 5 is calculated.
It is determined whether the supply of n has been completed. In this embodiment, this determination is made by determining whether or not the energization time from the start of energization in step ST14 has reached the energization time corresponding to the correction power amount Pn determined in step ST13. It is performed by And step S
At T6, when it is determined that the supply of the predetermined amount of power Pn to the heating element 5 has been completed, the process proceeds to step ST7, where the energization is stopped, and the process proceeds to step ST8. Be started.

As described above, according to the present embodiment, the power supply 17 is used at the next time of thread trimming based on the time from the previous thread trimming to the next thread trimming measured by the thread trimming interval detection timer 20 as the time measuring means, ie, the thread trimming interval. Since the CPU 12 controls the amount of electric power supplied to the heating element 5 from above, the maximum temperature of the heating element 5 by energization can be raised only to a temperature at which good thread cutting can be performed. As a result, thread cutting of the highest quality can be reliably performed, and the life of the heating element 5 can be extended.

Further, since reliable thread cutting can be performed, the sectional area of the heating element 5 can be reduced, the manufacturing cost of the heating element 5 can be reduced, and the electric capacity of the power supply 17 can be reduced. Can be.

FIG. 4 shows the temperature change of the heating element 5 at the time of each thread cutting according to the above-described embodiment. According to the embodiment, about half of the conventional maximum temperature difference of 130.degree. A maximum temperature difference of 70 ° C can be achieved.

In the embodiment described above, the amount of power supplied to the heating element 5 is controlled by the duration of the current supplied to the heating element 5, but the current supplied to the heating element 5 is controlled. Control the voltage of the
The amount of power can also be controlled by adjusting the duty cycle of the power-on time when power is supplied to the power supply, that is, by adjusting the ratio of the ON duty. Therefore, in the present invention, the control of the amount of power supplied to the heating element 5 is performed by controlling at least one of the conduction time of the current supplied to the heating element 5 and the ratio of the voltage and the ON duty of the conduction time. Can be performed.

Table 3 shows an example of a heating time control table for the ON duty ratio of the energizing time described above. This table shows the predetermined energization time (for example, 270 ms)
Represents the ON duty ratio of the energization time within the range. Therefore, instead of the heating time control table 13A shown in Table 2 previously stored in the memory 13, the one shown in Table 3 may be used. Also in Table 3, as in Table 2, only three heating levels, levels 1, 3, and 5, among the six heating levels that can be selected are described for convenience, and the other heating levels 2, 4, and 6 are described. Was omitted.

[0041]

[Table 3]

Even if the ON duty ratio shown in Table 3 is used, an appropriate energizing time of the heating element 5 can be obtained, so that the same effect as in the above-described embodiment can be obtained.

Note that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary.

[0044]

As described above, according to the sewing machine thread trimming apparatus of the present invention, the heating element can be raised only to a good temperature for thread trimming, and good thread trimming can be performed. The life of the heating element can be extended.

That is, the power supply means for supplying power by supplying power to the heat generating element during thread trimming, and the power supply means for starting the power supply to the heat generating element from the previous thread trimming to the next thread trimming. And a control means for controlling the amount of power supplied to the heating element by the power supply means at the time of the next thread trimming based on the time measured by the time measurement means. The control means controls the amount of power supplied to the heating element by the power supply means at the time of the next thread trimming based on the time from the previous thread trimming to the next thread trimming. Can be raised only to a temperature at which

Further, the control means controls at least one of an energizing time of a current applied to the heating element, a duty cycle of the energizing time at the energizing time, and an energizing voltage based on the time measured by the time measuring means. By controlling the amount of electric power supplied to the heating element by the current supply means at the time of thread cutting, the current supply time, the duty cycle of the current supply time, and a suitable element among the different elements of the current supply voltage, The supplied electric energy can be controlled stably.

Further, if the control means corrects the amount of electric power supplied to the heating element to a predetermined reference amount based on the time measured by the time measurement means, short energization in which the maximum temperature of the heating element tends to increase. At the time of the interval, for example, a power amount corrected to a value smaller than the reference amount is supplied to the heating element, so that the maximum temperature of the heating element can be controlled more stably.

Further, if a reference amount setting means for setting a predetermined reference amount by operation is provided, the predetermined reference amount can be easily set.

Further, the control means supplies a predetermined amount of electric power to the heating element by the power supply means at the time of the first thread trimming after the power supply to the sewing machine is turned on, and the time measured by the time measuring means at the next and subsequent thread trimmings. If the predetermined amount of time is exceeded, control is performed so that the amount of power supplied to the heating element is equal to the predetermined amount of power, whereby control of the amount of power supplied to the heating element can be simplified. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a control system showing an embodiment of a thread trimming device of a sewing machine according to the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment of FIG. 1;

FIG. 3 is a graph showing a correlation between a clock time and an energization time in the embodiment of FIG. 1;

FIG. 4 is a graph showing a temperature change of the heating element of the embodiment of FIG. 1;

FIG. 5 is a bottom view showing an example of a conventional thread trimming device of a sewing machine.

FIG. 6 is a view similar to FIG. 5, illustrating a thread cutting state in FIG.

FIG. 7 is a front view for explaining a thread cutting state in FIG.

FIG. 8 is a block diagram of a control system in the thread trimming device of the sewing machine of FIG. 5;

9 is a graph showing a temperature change of a heating element of the thread cutting device of the sewing machine of FIG. 5;

[Explanation of symbols]

 Reference Signs List 1 sewing machine 2 thread cutting device 5 heating element 6 sewing thread 7 catching member 10 control means 11 control panel 12 CPU 13 memory 13A heating time control table 14 control circuit 15 CPU board 16 switch section 17 power supply 19 heater transformer 20 thread cutting interval detection timer

Claims (5)

[Claims] 1. A thread trimming device for a sewing machine which cuts a sewing thread by bringing a sewing thread into contact with a heating element, a power supply means for supplying power by supplying electricity to the heating element at the time of thread trimming, and a next thread from a previous thread trimming. A time-measuring means for measuring a time until power supply to the heating element is started by the power-supplying means at the time of cutting; andthe power-supplying means at the time of the next thread trimming based on the time measured by the time-measuring means. A thread trimming device for a sewing machine, further comprising control means for controlling an amount of electric power supplied to the heating element. 2. The control means controls at least one of an energization time of an electric current applied to the heating element, a duty cycle of the energization time at the energization time, and an energization voltage based on the time measured by the time measurement means. By doing
The thread trimming device for a sewing machine according to claim 1, wherein the amount of electric power supplied to the heating element by the current supply means during thread trimming is controlled. 3. The control device according to claim 1, wherein the control unit corrects an amount of power supplied to the heating element to a predetermined reference amount based on a time measured by the time measuring unit. A thread cutting device for the sewing machine according to the above. 4. The thread trimming device for a sewing machine according to claim 3, further comprising a reference amount setting means for setting the predetermined reference amount by operation. 5. The control means supplies a predetermined amount of electric power to the heating element by the power supply means at the time of the first thread trimming after the power supply to the sewing machine is turned on, and the time is measured by the timing means at the next and subsequent thread trimmings. 2. The thread trimming device according to claim 1, wherein when the measured time exceeds a predetermined time, control is performed such that an amount of power supplied to the heating element is set to the predetermined reference amount. apparatus.